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Dupple writes in with some news from the team at the Large Hadron Collider. "Researchers at the Large Hadron Collider have detected one of the rarest particle decays seen in Nature. The finding deals a significant blow to the theory of physics known as supersymmetry. Many researchers had hoped the LHC would have confirmed this by now. Supersymmetry, or SUSY, has gained popularity as a way to explain some of the inconsistencies in the traditional theory of subatomic physics known as the Standard Model. The new observation, reported at the Hadron Collider Physics conference in Kyoto, is not consistent with many of the most likely models of SUSY. Prof Chris Parke, who is the spokesperson for the UK Participation in the LHCb experiment, told BBC News: 'Supersymmetry may not be dead but these latest results have certainly put it into hospital.'"

The summary, like the article, jumps straight into "OMG CONFLICT" without bothering to tell us what's going on. From later in the article:

Researchers at the LHCb detector have dealt a serious blow to [supersymmetry]. They have measured the decay between a particle known as a Bs Meson into two particles known as muons. It is the first time that this decay has been observed and the team has calculated that for every billion times that the Bs Meson decays it only decays in this way three times. If superparticles were to exist the decay would happen far more often. This test is one of the "golden" tests for supersymmetry and it is one that on the face of it this hugely popular theory among physicists has failed....

The results are in fact completely in line with what one would expect from the Standard Model. There is already concern that the LHCb's sister detectors might have expected to have detected superparticles by now, yet none have been found so far.

But it sounds like this is only a problem for some variants of supersymmetry:

"If new physics exists, then it is hiding very well behind the Standard Model," commented Cambridge physicist Dr Marc-Olivier Bettler, a member of the analysis team. The result does not rule out the possibility that super particles exist. But according to Prof Parkes, "they are running out of places to hide". Supporters of supersymmetry, however, such as Prof John Ellis of King's College London said that the observation is "quite consistent with supersymmetry". "In fact," he said "(it) was actually expected in (some) supersymmetric models. I certainly won't lose any sleep over the result."

But it sounds like this is only a problem for some variants of supersymmetry:

Yes and no. You can always change the theory to adapt, but if you continue to do that, at some point it stops being science, see http://www.stephenjaygould.org/ctrl/popper_falsification.html [stephenjaygould.org] . SoSY has been counterproven by several different experiments now, they are slowly but steadily running out of all the nice versions, and they have never had any positive confirmation. All it relied on was that it could be nice model if it wa

> if a theory is so general it can not be falsified it is not science.

Yes, but "supersymmetry" isn't "a theory", it's not the science. It's a label that is applied to the whole family of putative theories that are trying to be science, and which share a common core feature. It's not "general", it's "several". I hate to stand up for supersymmetry, as none of its expressions show the elegance that I like in science (et gustibus non disputandem est), but thinking of it as one single target that can be shot down is in error.

Not long before Newton some other guy (Galileo?) proposed the acceleration of objects falling under gravity such that the speed was proportional to the disance already moved. Newton as we know modelled it differently. The other guy's theory fell down when it was realised that an object would never start to fall. So they shot it down, and Newton's took over. That didn't mean that "gravitational acceleration" was so general it couldn't be disproved and wasn't a science.

> it makes it less interesting science

In some ways, definitely - yours seems to overlap somewhat with my 'elegance' point of view. If there is enough room to be making many many different models, then it looks like there's more guesswork involved than insight. Anyone can roll their own supersymmetric theory - download the new SuSy model GUI-based wizard trial version, and generate your own model in only 10 clicks! First 20 models free!

Science in reality isn't quite that simple. SUSY theories can be falsified (a big swath of them will be falsified when they increase the confidence on this observation). SUSY as an idea is much more difficult to falsify, just like the idea of a geocentric solar system is quite difficult to falsify. However, just like with geocentrism, when observations force you to resort to extremely complicated theories incorporating your idea, and other, very simple theories without your idea are available that also f

All supersymmetric theories may eventually be falsified, but that effort won't be wasted. Not only will we have ruled out a large family of possibilities for physics beyond the standard model, we will have also developed quite a lot of applied maths which may find applications in other areas. Either way, we win.

Like fatphil, I suspect it will be falsified. Failing that, if it's confirmed, then I suspect that it will eventually (though possibly not in our lifetimes) turn ou

But it sounds like this is only a problem for some variants of supersymmetry:

Yes and no.

Actually just 'yes'. SUSY is essentially a mirror image of the Standard Model about which we know very little indeed (only limitations on it). Hence the best models assume nothing which is not expressly forbidden and so we end up with ~120 free parameters vs the 25 free parameters for the Standard Model which we have measured and so excluded many of the possibilities. For example the we set the mass of a photon and a gluon to zero in the Standard Model because we have no evidence that they have a mass and the Lagrangian requires zero mass for it to have the correct symmetries. However in fact all we can do is put an upper limit on the mass from experiment: this is a better example of the illustration you are trying to make.

The Standard Model already heavily suppresses Bs->mumu decay all this has shown is that SUSY, if it exists, likewise heavily suppresses it. This is a very interesting result but, far from falsifying SUSY, it just means that SUSY is perhaps more like the Standard Model than we think it needs to be. Since we have no clue about how Supersymmetry is broken this is not too surprising...so I'd say it's very interesting and certainly constrains SUSY but it is by no means its death knell. Indeed arguments about excluding phase space and so therefore making a theory less probably are somewhat akin to arguing that choosing the numbers 1,2,3,4,5,6 in a lottery is stupid because they will never come up. If SUSY is there nature has chosen one set of parameters for it and, if that happens to be the last place we look it is the last place we'll find it. However if we find no hints of SUSY particles at the LHC once we run with a higher energy (March 2015) then it will start to be in trouble because at that point it becomes a less likely solution to the problem it was actually invented to explain: why is the Higgs mass so much less than the energy scale of gravity?

One of the unsatisfying properties of the standard model is its large number of free parameters. A replacement which has approximately five times as many doesn't seem too desirable to me. Generally, the less free parameters you have, the better. You know, with enough free parameters, you can fit an elephant.

I may be wrong, QM isn't my area of expertise, but I believe many of the, for example, superstring theories are attempts to "nail down" a lot of the free parameters by giving them physical meaning/making them emergent properties of the theory. In that case it's a situation of the current theory is full of ugly free parameters - but not enough of them to flex into an elegant theory consistent with observations. In which case adding a bunch of additional free parameters may actually allow you to nail them a

A replacement which has approximately five times as many doesn't seem too desirable to me.

Actually I used to feel the same way - that ultimately we should have a theory with 0-1 free parameters until a colleague pointed out another possibility. Suppose you have a universe where there are many free parameters but, ultimately, the physics ends up being pretty similar regardless of their actual choice? Since then I've been a lot less hung up on the idea of free parameters despite the fact that neither scenario is applicable to SUSY!

The next big step is for them to 'prove' that what they found has more than just the mass they were expecting for the Higgs Boson. Just because something has the proper mass +/- some orders of magnitude, that was in a *very* wide ball park of their proposed Higgs, doesn't mean that it does what the Higgs is supposed to do. How they are going to actually prove that it gives all the other particles their mass, given they only know of its existence due to its decay mode (as in its already gone), is going to be one rather tough problem. We better get started...

They know a bit more than the mass. They know that its spin is either 0 or 2, and they know the relative probabilities of some of the decay paths. Last I heard (this summer, right after the announcement), the proportions of the decay paths were a bit off, but more observations might put it back on track.

I don't know enough about QCD to say for sure, but given that the atomic binding energies are proportional to the electron mass, I'd be far from surprised if also the binding energy of nucleons depended critically on the quark masses, probably even to the point of proportionality (assuming you scale all masses the same).

That's where the mass "comes from", but doesn't explain why it has an effect. The Higgs field is an attempt to explain inertia in terms of particle physics - that is to say it is what causes the abstract concept of "mass" to have a physical effect in terms of resistance to acceleration, a.k.a. inertial mass.

Incidentally the Higgs does not (as I understand it) have anything to do with *gravitational* mass, either active or reactive. We're still looking for the theory to tie those together. A graviton migh

Yes, the binding energy of protons and neutrons to each other lowers the mass of a nucleus, such that a carbon-12 atom has less mass than 6 separate protons and 6 separate neutrons, but there is also the binding energy of the three quarks within each proton and each neutron. That is a honking big positive number, such that most of the mass (somewhere close to 99% [wikipedia.org]) is actually from the interaction (virtual gluons and such) between the quarks, rather than the rest mass of the quarks themselves. Since 99.9% of the mass of an atom comes from the protons and neutrons, about 99% of the mass of any object you interact with daily comes not from fundamental particles, but rather the energy of interaction between quarks.

So when the GP says "between and within protons and neutrons", he's correct, although dropping the "between" would make him slightly more accurate. I don't know enough about QCD to make any assessment of whether the Higgs field contributes significantly to the magnitude of that binding energy. (That is, if we had a zero-valued (or near-zero valued) Higgs field, would the magnitude of the quark binding energy (and thus the mass of everyday objects) be significantly different. )

Well, assuming that something is found that is not consistent with the standard model. There is actually something from the LHC that is not consistent with the standard model, the LHCb discovery of CP violation in charm decays [blogspot.com]. This is "only" 3.5 sigma, and needs some serious theoretical work to be sure the SM prediction is even right, but as things stand it is evidence for new physics [arxiv.org].

Between this and the (possible) discovery of the Higgs Boson, we may be about to launch into a new era of particle physics theory and research.

Actually, I think it's the reverse. Between this and the (possible) discovery of the Higgs Boson, we have simply just confirmed the parts of the standard model that we think we already understand. No new physics.

What people are actually looking for (and have found some hints/clues about like unexpected non-uniform decay paths in other experiments) are things that might suggests new physics that we don't understand at all which would launch a new era of particle physics theory and research. Some physists

The summary isn't detailed enough to bring this up, but TFA tries to equate supersymmetry with dark matter, which is emphatically wrong. The existence of dark matter is strongly supported by astronomical evidence including galaxy rotation velocities and observations of gravitational lensing, regardless of the nature of the particles that make it up. Even if this result provides evidence against supersymmetry (which doesn't seem to be the conclusion of other articles I've read, although I'm not really qualif

Even if this result provides evidence against supersymmetry (which doesn't seem to be the conclusion of other articles I've read, although I'm not really qualified to say), it tells us absolutely nothing about dark matter.

Wrong. If it is evidence against supersymmetry, it tells us that dark matter is likely not composed of supersymmetric particles. Given that supersymmetric particles are one of the main hypotheses about what dark matter is composed of, I'd say it tells us very much about dark matter.

It was a conjecture! If you are going to define "Theory" as being supported by a preponderance of evidence, as we do when we say, "The theory of evolution." then we can't keep going around calling every damned conjecture a theory too.

In a nutshell: the Standard Model of particle physics, developed in the 60s and 70s, has once again been shown to be a remarkably robust and effective description of reality. Thus far, no proposed extension to the SM has been corroborated by any convincing evidence. However, there *are* problems with the SM - it's just the resolution of these problems is at present beyond us.

It always baffles me why everybody is so focused on developing completely new and revolutionary physics. The greatest progress has been made in refining the Standard Model, rather than replacing it. And it always amuses me when people exhibit surprise when the Standard Model holds up. There cannot be such complexity in the universe if the fundamentals are constantly in disarray.

Perhaps it's because Einstein was their role model, and nobody in the next hundred years is going to quite make the dent in physics as Einstein did even though everyone is going to try. Nobody remembers that there was 300 years between Newton and Einstein, and that people 300 years ago were just as smart and just as capable as people today, only with fewer opportunities for the unprivileged individual and slower methods of communication between intellectuals.

Unfortunately, wild theories and postulations are not going to get where people want to go. Einstein's revolution was sparked by a moment of insight. It's not something that can be forced out with extra hours pounding square pegs into round holes. It can be prepared for by building a solid foundation. But that amounts to keeping the rain barrels outside and ready to collect in a desert.

Forget the exotic theories (especially the untestable ones). Leave the speculation to the metaphysicists. Stick with the basics. Trying to initiate the next revolution in physics would be as futile as dancing for rain.

It always baffles me why everybody is so focused on developing completely new and revolutionary physics.

The fundamental problem with the standard model is gravity. In terms of particle interactions, they have it covered via the Higgs particle and gravitinos. But the standard model doesn't have curvature of space.

In terms of particle interactions, they have it covered via the Higgs particle and gravitinos.

Gravitons. Gravitinos are the supersymmetric partners of gravitons, which might not exist at all.

But the standard model doesn't have curvature of space.

That's not the fundamental problem. If you could consistently describe quantum gravity without space curvature and recover GR in the classical limit, physicists would happily put space curvature where they haver put absolute time: A nice approximation which works we

EU claims that the sun is powered not by fusion, but by a DC interstellar current. The induced magnetic field at 1 AU from a current of sufficient magnitude would far surpass the earth's magnetic field. A compass trivially disproves this.

The fundamental problem with the standard model is gravity. In terms of particle interactions, they have it covered via the Higgs particle and gravitinos. But the standard model doesn't have curvature of space.

But you can do quantum field theory in curved spacetime, i.e., without quantizing the gravitational field. There is no single experiment ruling out such a model. So I don't think gravity is a problem for the SM, it's rather our desire to find a unified description of all forces in nature. But of course, nobody knows whether such a unified theory will be correct in the end.

There are conceptual problems. Such as where did the space come from in your model? Or is space curved by your quantum effects (such as a non-zero vacuum energy)?

So I don't think gravity is a problem for the SM, it's rather our desire to find a unified description of all forces in nature. But of course, nobody knows whether such a unified theory will be correct in the end.

Any such description would be by definition unified. We have a number of unified descriptions now. They just don't work at the moment.

There are conceptual problems. Such as where did the space come from in your model? Or is space curved by your quantum effects (such as a non-zero vacuum energy)?

Spacetime itself does not have to come from somewhere as an emergent concept. It could just be there as it's currently the case with either GR or QFT. Spacetime could get curved via the expectation value of the energy-momentum tensor. No mathemetical ambiguities, no contradiction to experiments, and fully consistent with both GR and the SM. However, I would hardly call this a "unified" description of all forces. Nevertheless, arguing against such a description of nature on purely aesthetic grounds is a bit

Spacetime could get curved via the expectation value of the energy-momentum tensor.

Then you have to match the two. That creates a coupling between your model and your background. Not impossible, but also not something that's been done yet.

OTOH, if we can come up with a working model where spacetime is an emergent concept, then that would probably be a more fundamental description and also a model where the above problem of getting curvature to agree with the energy-momentum tensor happens naturally.

There's Rivelli's book, Quantum Gravity, where he quantized the gravitational field and gets space-time to emerge as the eigenstates of the relevant operators. Warning: the subject matter is deep both conceptually and mathematically. Not for easy casual reading.

The greatest progress has been made in refining the Standard Model, rather than replacing it.

Which is why a lot of folks were gunning for SUSY, because that's more or less exactly what is -- an extension, rather than a replacement, for the Standard Model.

In SUSY we keep everything we already know and love about the Standard model, but there is also a symetry where each existing particle has a partner with 1/2 spin difference.

Which as a consequence would apparently solve a number of known issues with the Standard Model -- which is attractive because we know the SM is good, but flawed -- and also provide possible solutions for other mysteries like Dark Matter.

So, basically, rulling out SUSY would be a setback for the (very reasonable and desireable) "refinement" model of advancing physics.

Maybe you're going off the fact that String Theory, a revolutionary new model of physics, also predicts SUSY?

Because the greatest offshoot of SUSY is string theory. String theory relies on SUSY being true, and academic institutions are stuffed with string theorists making ever more grandiose claims about what string theory predicts (think Sheldon Cooper times a billion) without a single prediction of an experimental result that unambiguously proves string theory is correct.

I expect a petition by string theorists to turn off the Large Hadron Collider any day now.

I'm not a physicist, and to me, a lot of this seems like wishful thinking : building on a model of a model, without any actual proof that any of it is actually correct.

We have an enourmous amount of experimental evidence that a huge number of predictions of the Standard Model are correct to ridiculous degrees of precision. No matter what happens, that mountain of evidence is not going to go away.

You can't literally "prove" physical theories; proof is for math. You can only acquire evidence based on observation. And there is precious little else in all of science that has as much hard quantitative evidence for it than the Standard Model.

Accepting that you meant "proof" in the sense that is applicable to physics, it's just ludicrous to say we're building on a model "without any actual proof".

The theory also isn't perfect as there are phenomenon it does not explain, but given its enourmous success, doesn't it make sense to build on it to iron out the imperfections? It's not like this is being done to the exclusion of complete reworks. Physicists around the world are working on the problem from various angles. It would be outright stupid to ignore the "Standard Model is basically correct but needs extending to cover the new phenomenon" angle.

It seems like a lot of fun, but why does it surprise anyone if it comes crashing down one day ?

Two different answers:1) Because if the theory was really that bad that it was going to come "crashing down", then it wouldn't have been so fantastically successful up to this point.

2) It wouldn't be a surprise if the next-better-theory does away with the Standard Model completely as the most accurate description of reality, because this has happened before and will probably happen again. However, just like with the theories those two supplanted, the Standard Model would not so much come "crashing down" as be shown to just be an approximate model that works extremely well for a broad range of conditions and to extremely high precision. It is essentially impossible for this not to be the case because we've already tested it in that range. Any replacement theory must give the same predictions for the same conditions, or that theory is not a good replacement.

This might be a legitimate argument if it were not for the fact that the Standard Model has its own particular issues, and all these attempts to extend it, no matter how much you (whoever the fuck you are) may not approve are ways to try to solve those problems.

> Nobody remembers that there was 300 years between Newton and Einstein, and that people 300 years ago were just as smart and just as capable as people today,
And less distracted by slashdot, facebook, twitter and other interweb stuff that detracts from serious thought

Why do techies completely miss that point, then, when the difference is 2000 years, and the subject is things for which they would have more experience than us?

This techie (engineer) doesn't. I must admit having a Mom who's an anthropologist, having spent time in the field, and listened to whole buildings full of archeologists as well, might have colored my outlook. Just a smidgen.

I can't speak for anyone else, but my ancestors weren't stupid. And we still can only guess at how they went about doing the "impossible" to this day. At least if civilization ends soon, I'll be one of the few that can make my own damn tools! [It probably would have helped if a cert

It all started when Maxwell's equations gave results that did not agree with newtonian physics. In an attempt to get at the root of things, Michelson and Morley [wikipedia.org] created an experimental setup to measure the speed of light in different directions in a very precise way. To everyone's astonishment, these experiments indicated that the speed of light is a universal constant, which does not depend on either the movement of the light emitter nor the movement of the detector.

Which was exactly what Maxwell's equations had predicted to begin with! If there was a true intellectual giant here, it was Maxwell.

Several scientists started creating equations that made the results of the Michelson-Morley experiment compatible with classical mechanics. Einstein was just the most successful one, because his equations were more elegant and simpler than those of the others.

However, this does not mean Einstein was absolutely right, his theory was only the best one for that particular period. Today we know things he didn't know, just as Newton didn't know that the speed of light is constant.

For instance, there IS a fixed frame for the whole universe, the one in which the cosmic background [wikipedia.org] is symmetrical. This background was discovered only in 1965.

There's also the horizon problem [wikipedia.org], which was discovered only in the 1970s. If we look at the sky in opposite directions, we see the same characteristics. We are looking at different regions of the universe that never had contact with each other since the creation of the universe. They are so far apart that even light couldn't have reached one from the other during the universe's lifetime. To solve this problem in a way that's compatible with einsteinian relativity, cosmologists came up with cosmic inflation [wikipedia.org], a rather ugly and contrived kludge.

Besides, relativity does not give results that are compatible with quantum physics, this has been demonstrated experimentally [wikipedia.org].

It's rather unfortunate that Einstein's theory is so elegant and precise, because it's certainly wrong when your size scales too much up or down.

From a personal perspective, this post makes me sad. No offense at all to mangu, you are quite correct in what you've said, it is just that Einstein was really the last physicist to give a new theory that was explained both mathematically and metaphysically. He said what was happening and also why.

Ever since it has been maths only and no explanation as to what is actually happening.

I know why this must be the case, and Neils Bohr was right and my human brain's need for narrative and context is wrong, but I

Futility? Really? The SM is incomplete, in that you have to plug and chug 17 constants that can only be determined via observation. This incompleteness may not be wrong, per se, but it certainly means that refining the SM is unlikely to be the optimal path towards truth. What is the optimal path? You tell me. But spending a lot of resources on a theory that is known to be incomplete and can never be made complete, when there exist other theories that don't have those issues, sounds like the very defin

I believe one of the big motivations is that while the Standard Model does a good job of *describing* our current observations (excepting gravity), it doesn't do anything to *explain* them. Unlike every other area of science where the fundamental laws are accompanied by a theory that gracefully explains *why* those laws describe observations, the SM simply consists of a bunch of component "particles" and some apparently completely arbitrary constants governing their behavior. Couple that with the act that

SUSY is an extension to the standard model, not a replacement. Most new physics is an extension. Even string theory can be seen as sort of an extension, albeit one that (attempts) to add a lot of explanatory power as well.

The standard model needs to be extended - we know it's incomplete. SUSY would resolve some problems with the model and also introduce some good candidate particles for dark matter.

Don't doubt Einstein did a lot of pounding pegs. His theories didn't spring fully formed out of his head a

Not quite. Einstein didn't work in a vacuum. There were plenty of other scientists working on exactly the same problems he was. Including lots and lots of "wild theories and postulations." Einstein's great insight was to put it all together in a way that happened to work.

If his formulation had turned out to be wrong, we'd be holding up someone else as the pinnacle of physics -- possibly even still Newton.

As for 300 years -- you're absolutely right on that. But you skim over the obvious problem with tha

No, the "observed" distribution of dark matter wouldn't occur unless it doesn't interact with normal matter except gravitationally, and possibly not with other dark matter either - none of the "particles" in the SM exhibit those properties. If the SM is correct and complete (and we know it isn't, we've already discovered problems) then that would mean that dark matter almost certainly doesn't exist and the various phenomena which suggest its existence are due to some other effect. There's lots of alternativ

Another thing that is missing from the Standard model is an understanding of how the basic forces interact with each other. For example, if the strong and weak forces interact in some way, then there would be a decay pathway [wikipedia.org] for the proton. The standard model doesn't rule this out.

The LHC data are beginning to impinge on the Minimal Supersymmetric Standard Model [wikipedia.org]. One of the attractions of the MSSM is its "naturalness," which is beginning to seem less natural [arxiv.org]. The the lightest superparticle (LSP) of the MSSM is a dark matter candidate of the WIMP (Weakly interacting massive particle) variety, and WIMP searches are beginning to impinge on the "naturalness" of that explanation too.

Of course, after the confirmation of a non-zero cosmological constant, the arguments from naturalness see

The standard model as a theory on its own needs extreme fine tuning to be valid all the way up to the scale where gravity becomes strong. Technically, there is a quadratic dependence on the upper scale of the theory when one calculates the quantum corrections to the Higgs mass. This leaves the theory very unnatural (even though mathematically not impossible).
Supersymmetry solves this naturalness problem by canceling the quadratic divergences. It cannot cancel exactly though (or we'd have observed supersumm

The standard model as a theory on its own needs extreme fine tuning to be valid all the way up to the scale where gravity becomes strong. Technically, there is a quadratic dependence on the upper scale of the theory when one calculates the quantum corrections to the Higgs mass. This leaves the theory very unnatural (even though mathematically not impossible).
Supersymmetry solves this naturalness problem by canceling the quadratic divergences. It cannot cancel exactly though (or we'd have observed supersummetry since long), so therefore a new unnaturalness problem arises when supersymmetry lives at an energy scale far above the scale of electroweak symmetry breaking (~the Higgs boson mass scale).

And that wouldn't be the case no matter what sort of universe was observed?

It can be thought of as an attempt to do probabilistic type arguments, when you don't have any data to do probability with.

Suppose that astronauts find a long abandoned alien base on the Moon. All equipment was carefully removed, but we know that the doors and corridors are all 4 meters wide and 3 meters high. It would be "natural" to assume that the aliens (or their machinery) were typically less, but not much less, than 3 meters tall. That could be wrong - maybe they are 1 meter birds who like room to fly in. Or maybe they are 4 meter giants who don't mind stooping. But, in the absence of any other evidence, it is a "natural" assumption. Such assumptions are very common in places like cosmology and quantum gravity.

One argument from naturalness is that dimensionless constants should "naturally" be near one, without a good reason to have some specific value. (The other "natural" is of course zero.).

Take the axion and CP violation. You can add a term to the QCD Lagrangian which violates Charge+Parity (or CP), which means that this term allows for particles and their antiparticles to behave differently. This term is multiplied by a constant denoted by theta, with theta = 0 meaning no CP violation. It turns out you can restrict theta to be 10^-10 experimentally. So, presumably, theta IS zero (as zero is a much more "natural" number than the really tiny 10^-10). The axion came from assuming that theta really described a new field (with a new particle, the axion), and was driven towards zero in the evolution of the universe. It seemed much more "natural" to say that "after about the first microsecond of the big bang theta is driven to be zero" than just saying "this constant is really tiny."

The reason I said that about the cosmological constant (lambda) is that it is about 0.7 and (in the same units) the standard model value for it is about 10^122. (Or,in natural units, its current value is about 10^-122.) That is an extraordinary result. Many people were sure that lambda was exactly zero (as that could also be "natural,") but it isn't. Note that the value for the axion's theta is by contrast almost routine. If theta is like winning the lottery, lambda is like having every atom in the universe winning the lottery simultaneously for every nanosecond that the universe has existed. So, I regard these arguments as less persuasive than I did 20 years ago,

In a fairly hand-wavy way, supersymmetry predicts we should see this quite a lot, but the experiment shows it happens far less frequently, implying the current version of SUSY is either incorrect or completely wrong.

No, many current variants of SUSY predict we should see this quite a lot. Other versions agree with the SM.Quite a few variants of SUSY can be ruled out, others are still viable. Quite a lot of string theory variants can also be ruled out, and a few theories involving extra dimensions (Kaluza-Klein partner particles would likely alter this result, though it is not sensitive enough to rule out a lot of these interactions.)That doesn't mean SUSY is wrong, or that string theory is wrong, or that extra dimensio